Re: Python 2 support in GNOME build tools

[Simon McVittie <smcv collabora com>]

On Thu, 12 Jul 2018 at 09:29:26 +0200, Christoph Reiter via desktop-devel-list wrote:
> we currently do support Python 2 and 3 for things like gobject-introspection
> and glib scripts etc. and while I don't see any problem with continuing that
> support I'd like to know why we still need to support Python 2 there. i.e.
> What needs to happen so that Python 3 support is enough for everyone?

Slow-releasing/stable/"enterprise" distributions like RHEL, Debian,
Ubuntu LTS and SLED are the usual sticking point for dependency versions.

My understanding is that the main blocker for using Python 3 is
that RHEL/CentOS 7 doesn't have it built-in, only as part of a secondary
"software collection"?

For what it's worth, requiring Python 3 would be no problem from Debian's
perspective, as long as it isn't assumed to be /usr/bin/python: for
compatibility with historical scripts, if /usr/bin/python exists then
it is always Python 2, while Python 3 is available at /usr/bin/python3
if installed. Using Python 3 for all programs that can work in either
version is recommended, and in particular we've used Python 3 for the GLib
and GObject-Introspection build tools since Debian 9 'stretch' (2017).

We don't normally backport the latest GNOME versions to stable releases
anyway; but if we do, the latest stable release (Debian 9 'stretch')
has Python 3.5 as its supported Python 3 version, and the one before that
(Debian 8 'jessie', 2015) had 3.4.

Ubuntu is in about the same situation as Debian, with new LTS releases
every 2 years, although a year out of phase with Debian (the most recent
LTS releases were in 2018 and 2016 and have contemporary Python 3 versions).

    smcv